kern/78227: Destroying a network interface leaks kernel memory

[Yar Tikhiy]

>Number:         78227
>Category:       kern
>Synopsis:       Destroying a network interface leaks kernel memory
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Mar 01 06:20:15 GMT 2005
>Closed-Date:
>Last-Modified:
>Originator:     Yar Tikhiy
>Release:        FreeBSD 6.0-CURRENT i386
>Organization:
MSU
>Environment:

5-STABLE, 6-CURRENT

>Description:

It was originally reported by Oleg Bulyzhin <oleg <@> rinet <.> ru>
that destroying a vlan(4) interface with an assigned IP address would
leak kernel memory.

Further investigation has shown that the problem isn't specific to
vlan(4) and affects any multicast interface.  The system just doesn't
seem to leave the "all hosts" multicast group upon dismantling an
interface.

In my case, each plumb/unplumb cycle on a vlan(4) interface leaks
1 in_multi memory block and 5 ether_multi blocks.  For lo(4) the
amounts are 1 and 2, respectively.

>How-To-Repeat:

# change lo11 to vlanXX and add vlan/vlandev to the create command to test on vlan
vmstat -m > vmstat-m.0
for n in `yes | head -1000`; do
	ifconfig lo11 create inet 1.1.1.1/24 up
	ifconfig lo11 destroy
done
vmstat -m > vmstat-m.1
diff vmstat-m.0 vmstat-m.1

>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted: